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SDC-361/362
16-BIT, TWO SPEED SYNCHRO-TO-DIGITAL AND RESOLVER-TO-DIGITAL CONVERTER
FEATURES
DESCRIPTION
The SDC-361 is a low-cost, single module synchro-to-digital (S/D) and resolver-to-digital (R/D) tracking converter. A unique control transformer algorithm is used that provides inherently higher accuracy and jitter-free output. Other features include a BIT logic signal to indicate proper tracking and an analog velocity output. Utilizing a type II servo loop, these converters have no velocity lag up to the specified tracking rate, and output data is always fresh and continuously available. Each unit is fully trimmed and requires no adjustment.
APPLICATIONS
The SDC-361 may be used wherever analog angle data from synchros or resolvers must be converted rapidly and accurately to digital form for transmission, storage and analysis. Because these units are extremely rugged and stable, and meet the requirements of MIL-STD-202E, they are suitable for the most severe industrial, commercial and military applications. Military ground support and avionics uses include ordnance control, radar tracking systems, navigation and collision avoidance systems.
* Accuracy: 1 LSB = 20 Seconds * SIGNAL AND REF INPUTS:
- Internal Transformer Isolation - Broadband Input: 350-3000 Hz or 47-3000 Hz - All common L-L voltage levels
* LOGIC:
- TTL Compatible - 16-Bit Parallel Binary Angle Output, and Converter Busy, Inhibit and BIT
* POWER REQUIREMENTS:
- 15 VDC and +5 VDC
SIN ( - ) SIN 36 ( - ) 36X SYNCHRO INPUT S1 S2 S3 SCOTT-T TRANSFORMER CONTROL TRANSFORMER CT COS 36 36 36X OR 1X RESOLVER INPUT OPTION: S1 RESOLVER S2 INPUT S3 S4 RESOLVER ISOLATION TRANSFORMER SIN COS 16 BIT UP-DOWN COUNTER (CONTAINS ANGLE ) 36X DIGITAL MULTIPLIER SIN 36 STICKOFF
+
CROSS-OVER DETECTOR ERROR R ( - ) ERROR PROCESSOR AND VOLTAGE CONTROLLED OSCILLATOR
REFERENCE ISOLATION TRANSFORMER
RH REF RL INPUT
VEL VELOCITY INH INHIBIT CB CONVERTER BUSY DIGITAL OUTPUT BITS 1to 16
1X SYNCHRO INPUT
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SCOTT-T TRANSFORMER
SIN COS
CONTROL TRANSFORMER CT
SIN ( - +2.5) CONTAINS 2.5 ANGLE OFFSET
NOTE: Block Diagram Illustrates SDC-361. All References to "36X" are "18X" for SDC-362.
FIGURE 1. BLOCK DIAGRAM
1980, 1999 Data Device Corporation
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TABLE 1. SDC-361/362 PARAMETER RESOLUTION ACCURACY SDC-361 SDC-362 SIGNAL AND REFERENCE INPUT (All inputs transformer isolated. Other freq. and volt. available.on special order. ) Synchro Input 90V L-L, 400 Hz (Option H) 90V L-L, 60 Hz (Option I) 11.8V L-L, 400 Hz (Option L) Resolver Input 90V L-L, 400 Hz (Option H) 26V L-L, 400 Hz (Option I) 11.8V L-L, 400 Hz (Option L)
SPECIFICATIONS VALUE 16 bits 1 LSB ( 20 sec) 1 LSB ( 40 sec) Signal Frequency Range Signal Input Impedance (L-L Balanced, Resistive) 148 Kohm min 148 Kohm min 19 Kohm min 148 Kohm min 42 Kohm min 19 Kohm min Reference Input Impedance (L-L Balanced, Resistive) 300 Kohm min 80 Kohm min
TABLE 1. SDC-361/362 SPECIFICATIONS (CONTD) VALUE PARAMETER DYNAMIC CHARACTERISTICS (Continued) Velocity Constant (Type II Servo Loop) Acceleration Constant Options H, M, L ( 400 Hz) Option I ( 60 Hz) POWER SUPPLIES Nominal Value Voltage Range Max Voltage without Damage Current Typical Maximum TEMPERATURE RANGES Operating -1 Option -3 Option Storage PHYSICAL CHARACTERISTICS Size 3.125 x 2.625 x 0.82 inches (79.4 x 66.7 x 20.8 mm) 7 oz (200 g) Kv =
KA = 70,000 Nominal KA = 4,300 Nominal
350-3000 Hz 47-3000 Hz 350-3000 Hz 350-3000 Hz 350-3000 Hz 350-3000 Hz Reference Frequency Range
+15 V +11.5 to +16.5 V +18 V 10 mA 15 mA
-15 V -11 to -16.5 V -18 V 35 mA 50 mA
+5 V + 4.5 to + 5.5 V +7 V 110 mA 150 mA
-55C to + 105C 0C to + 70C -55C to + 125C
Reference Input (Option H, I ) (Option M, L) DIGITAL INPUT/OUTPUT Logic Type Inhibit Input (INH) Loading
40-150 V rms 10- 50 V rms
TTL Logic "0" inhibits, 0.2 Std TTL loads plus 18 Kohm min pull-up resistor to +5 V supply. Natural binary angle; pos. logic 1-2.5 sec positive pulse, data changes on leading edge 2 Std TTL loads (Consult factory for 5 Std load capability) Logic 0 = normal tracking Logic 1 = not tracking within fine speed range 1.0 VDC 30% for 100/sec at 400 Hz 1.0 VDC 30% for 25/sec at 60 Hz 10 VDC min 10 Kohm max
Weight
Outputs 16 Parallel data Bits Converter Busy (CB) Drive Capabilitity BIT (Bilt In Test)
INTRODUCTION
The operation of a two speed S/D is essentially the same as a single speed module, except there are two control transformers (CT) which generate two error voltages. These two CTs are fed by a common up-down counter. The counter data is multiplied by 36 for an SDC-361 and 18 for an SDC-362 to generate the fine speed CT. Assuming an off-null condition as when the system is initially energized, the crossover detector feeds the coarse (1X) CT error signal output to the demodulator and error processor. The converter seeks a null as it would for a single speed S/D. As null is approached (to within 2.5 nominally) the coarse CT output drops below a preset threshold and the crossover detector then switches the fine CT error signal (36X for SDC-361, 18X for SDC-362) into the demodulator and error processor. Since the counter angle is multiplied by 36X for SDC-361, and 18X for SDC-362, the gradient of the fine speed CT is 36X the coarse output CT for the SDC-361, and 18X for the coarse output CT for the SDC-362. The servo loop then seeks a finer null, using the fine speed CT error signal. The converter continues to use the fine error signal for continuous tracking, and only switches back to the coarse signal when the coarse error exceeds the crossover threshold. To eliminate false stable nulls at 180, an angle offset and stickoff voltage are introduced in the coarse channel. The 15 V power supplies can vary over their specified ranges with no change in the converter specifications except for a proportional change in the maximum tracking rates. When testing or evaluating the converters, it is advisable to limit the current to each of the three power supplies. Set each current limit to 50% greater than the maximum current listed for that supply in TABLE 1. 2
ANGULAR VELOCITY OUTPUT Scale Factor
Range Loading DYNAMIC CHARACTERISTICS Input Rate for Full Velocity Options H, M, L (400 Hz) Option I (60 Hz) Acceleration for 1 LSB Lag Options H, M, L(400 Hz) Option I ( 60 Hz) Settling Time For Normal Tracking (Up to specified Input Rate) For 179 Step Change (Typical Values) Options H, M, L (400 Hz) Settling to 1 LSB Settling to Final Value Options I (60 Hz) Settling to 1 LSB Settling to Final Value
0-1000/sec minimum 0-250/sec minimum
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384/sec typ 23/sec typ
No Lag Error
400 msec 480 msec 1400 msec 1800 msec
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To prevent damage to the input transformers, the maximum voltage should not exceed the specified input voltage by more than 30%. The maximum common mode voltage (DC plus recurrent AC peak) should not exceed 500 V.
ANALOG VELOCITY OUTPUT
VEL is a DC voltage proportional to the angular velocity d/dt = d/dt. The output is derived from an op-amp with low output impedance and is short-circuit protected. Other characteristics are listed in TABLE 1.
DIGITAL INPUTS
Logic inputs are low power Schottky and the can drive remote loads. The BIT logic output is a built-in-test derived from the crossover detector. It goes to logic 1 whenever the digital output is not tracking the input signal within the range of the fine speed synchro or resolver.
TABLE 2. BIT WEIGHT BIT 1 MSB 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 DEG/BIT 180 90 45 22.5 11.25 5.625 2.813 1.406 0.7031 0.3516 0.1758 0.0879 0.0439 0.0220 0.0110 0.0055 MIN/BIT 10,800 5,400 2,700 1,350 675 337.5 168.75 84.38 42.19 21.09 10.55 5.27 2.64 1.32 .66 .33
DYNAMIC PERFORMANCE
A Type II servo loop (Kv = ) and very large acceleration constants give these converters superior dynamic performance, as listed in TABLE 1. If the power supply voltages are not the 15 VDC nominal values, the specified input rates for full accuracy will increase or decrease in proportion to the fractional change in voltage. The +15 V supply voltage will determine the maximum positive velocity. The -15 V supply voltage will determine the maximum negative velocity. As long as the maximum tracking rate is not exceeded, there will be no lag in the converter output. If a step input occurs, as is likely when the power is initially turned on, the response will be critically damped. After initial slewing at the maximum tracking rate of the converter, there is one overshoot which is inherent to a Type II servo. The overshoot settling to final value is a function of the small signal settling time. The loop dynamics of DDC's tracking S/D converters are described by the unity feedback configuration shown. The closed-loop transient response is nominally critically damped, and all loop dynamics can be determined from the diagram and formulas given.
TIMING
Whenever an input signal change occurs, the converter changes the digital angle in steps of 1 LSB, and generates a converter busy pulse (CB). The output data change is initiated at the leading edge of the CB pulse, and the output is stable within 0.2 sec after the leading edge. Extra CB pulses will not occur if the input angle changes while the counter is locked by the INH. The simplest method of interfacing with a computer is to transfer data at a fixed time interval after the inhibit is applied. The converter will ignore an inhibit applied during the "busy" interval until that interval is over. Timing is as follows: (a) apply the inhibit, (b) wait 0.2 sec, (c) transfer the data and (d) release the inhibit.
2
OVERSHOOT
1 SMALL SIGNAL SETTLING TIME MAX SLOPE EQUALS TRACKING RATE (SLEW RATE)
FIGURE 3. STEP RESPONSE INPUT
+ ANGLE INPUT e G DIGITAL OUTPUT
5.5 sec MIN DEPENDS ON d/dt CONVERTER " 1 " BUSY (CB) "0" INHIBIT (INH) "1" "0" DATA VALID
- UNITY FEEDBACK 1
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aSTABLE 2. TIMING DIAGRAM t
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At 60 Hz
At 400 Hz
662
0.2 sec VALID
(
S 33
+ 1) G=
2662 S2
(
(
G= S2
(
S + 1) 133 S + 1) 1330
S + 1) 330
FIGURE 4. S/D CONVERTER LOOP DYNAMICS
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ACCURACY TESTS
Because of the accuracy of DDC's S/D converters, only laboratory grade synchro or resolver substitution boxes or standards should be used. If synchro standards are not available, arrangements may be made to witness the final source inspection at the DDC factory. The figure below shows how to setup equipment to measure S/D converter accuracy. A separate lamp driver or suitable readout is required for each output data line. The synchro standard is set to any desired test angle, and the lamps which are lit are added according to their bit weights and compared with the test angle.
TEST METHODS FOR DISCRETE MODULES
All of DDC's discrete S/D converter modules are high quality products whose semiconductor components are hermetically sealed. Discrete modules will meet specific test methods and conditions of MIL-STD-202E shown below unless alternate methods are specified by the customer in his procurement documentation.
TABLE 4. MIL-STD-202E TEST METHODS CONDITION METHOD 204C C 213B A 106D * -107D A 101D B 105C B * when conformally coated on COMMENT 10G, 2000 Hz vibration 50G, 11 ms shock Moisture Thermal shock Salt spray 50,000 ft, altitude P.C. board
PRINTED CIRCUIT BOARD MOUNTING
When mounting a converter on a printed circuit board, it is very important to keep logic-level signals as far away from AC and power signal as possible. Under no circumstances should AC or power pins be adjacent to data pins at the connector. It is also prudent to keep the AC and power pins separated from each other. The intent is to make it impossible to short logic inputs/outputs to AC or power pins with scope probes, and to keep digital noise from coupling into the sensitive AC signals. It is strongly recommended that circuit layouts be designed so plated through-holes are not required to mount hybrid or discrete modules. If all lands connecting to pins are located on the opposite (dip) side of the PC board from the module, there will be no risk of destroying a connection by ripping out the plated throughhole connection if the module must be replaced. It will also be easier to unsolder the module without the module being damaged.
REFERENCE RH RL S/D OR R/D CONVERTER BEING TESTED SYNCHRO OR RESOLVER INPUT BIT I LAMP DRIVER BIT N LAMP DRIVER
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SYNCHRO/ RESOLVER STANDARD (SINGLE SPEED OR TWO SPEED)
FIGURE 5. ACCURACY TEST CIRCUIT
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2.625 .015 (66.7 0.4)
BIT VEL CB INH
*36X S4 36X S1 36X S3 36X S2
RL RH
26 SPACES @ .100 .010 = 2.600 (2.5 0.3 = 66.0) (TOL. NON-CUM.)
.262 .020 (6.7 .051)
.100 (2.54) (TYP)
16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
1X S3 1X S1 1X S2 *1X S4
3.125 .015 (79.3 0.4)
.025 .001 (0.6 0.03) SQUARE PIN (TYP) +15V -15V GND +5V
.162 .020 (4.1 0.5)
2.300 .010 (58.4 0.3)
.250 (6.4) (MIN)
.82(21) (MAX)
BOTTOM VIEW
Notes: 1. All reference to 36X become 18X on SDC-362. 2. Pin labels for reference only. 3. All dimensions shown in inches (mm). 4. Pin material meets solderability requirements of MIL-STD-202E, Method 208C. 5. Case material is glass filled Diallyl Phthalate per MIL-M-14, Type SDG-F. 6. S4 pins are present on resolver units only.
FIGURE 6. MECHANICAL OUTLINE ORDERING INFORMATION
SDC-361-H-I Temperature Range 1 = -55 to +105C 3 = 0 to +70C Signal Input Voltage and Frequency H = 90 V L-L, 400 Hz (Synchro or Resolver) I = 90 V L-L, 60 Hz (Synchro only) M = 26 V L-L, 400 Hz (Resolver only) L = 11.8 V L-L, 400 Hz (Synchro or Resolver) Speed 361 = 1 x 36 speed 362 = 1 x 18 speed Input Type SDC = Synchro RDC = Resolver
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The information in this data sheet is believed to be accurate; however, no responsibility is assumed by Data Device Corporation for its use, and no license or rights are granted by implication or otherwise in connection therewith. Specifications are subject to change without notice.
105 Wilbur Place, Bohemia, New York 11716-2482 For Technical Support - 1-800-DDC-5757 ext. 7389 or 7413 Headquarters - Tel: (631) 567-5600 ext. 7389 or 7413, Fax: (631) 567-7358 Southeast - Tel: (703) 450-7900, Fax: (703) 450-6610 West Coast - Tel: (714) 895-9777, Fax: (714) 895-4988 Europe - Tel: +44-(0)1635-811140, Fax: +44-(0)1635-32264 Asia/Pacific - Tel: +81-(0)3-3814-7688, Fax: +81-(0)3-3814-7689 World Wide Web - http://www.ddc-web.com
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C-03/97-500
ILC DATA DEVICE CORPORATION REGISTERED TO ISO 9001 FILE NO. A5976
PRINTED IN THE U.S.A.
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